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      <title>大型网站在架构上应当考虑哪些问题 - 交互式测验</title>
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    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>大型网站在架构上应当考虑哪些问题 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
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                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
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            </div>
          </div>
      </div>

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  {
    "question": "根据文档，当一个系统通过增加更多独立的服务器节点来提升其处理能力时，这种策略被称为什么？",
    "options": [
      "垂直扩展",
      "服务冗余",
      "水平扩展",
      "故障转移"
    ],
    "correctAnswerIndex": 2,
    "explanation": "水平扩展（Horizontal Scaling）的核心思想是通过增加更多的服务器节点来共同分担负载，从而扩展整个系统的容量。这与垂直扩展（Vertical Scaling）——即增强单个服务器的硬件资源（如CPU、内存）——形成了对比。",
    "source": "文档中「1. 系统可扩展性」部分的「水平扩展与垂直扩展」",
    "hint": "思考一下，当网站流量激增时，是让一台机器变得更“强壮”，还是增加更多的“帮手”？"
  },
  {
    "question": "在性能优化中，使用Redis或Memcached这类工具的主要目的是什么？",
    "options": [
      "将静态资源（如图片、视频）分发到离用户更近的节点",
      "在多个服务器之间均匀分配用户请求",
      "缓存热点数据和查询结果，以减少对数据库的直接访问",
      "对数据库进行分片，以提高读写性能"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Redis和Memcached是典型的内存缓存系统，它们属于“应用缓存”的范畴。其主要作用是将频繁访问的热点数据（如用户信息、商品详情）或耗时查询的结果存储在内存中，从而极大地提高响应速度，并减轻后端数据库的压力。",
    "source": "文档中「2. 性能优化」部分的「缓存机制」",
    "hint": "当一个数据被频繁读取时，我们希望从哪里获取它最快？"
  },
  {
    "question": "为了确保系统的高可用性，文档中提到的“主从复制”技术主要解决的是哪一类问题？",
    "options": [
      "服务冗余，确保应用在单个实例故障时仍可访问",
      "数据冗余，为数据提供备份和容灾能力",
      "负载均衡，防止单个数据库节点过载",
      "自动故障转移，自动将服务切换到健康节点"
    ],
    "correctAnswerIndex": 1,
    "explanation": "主从复制是一种常见的数据冗余策略。通过将主数据库的数据实时或异步地复制到一个或多个从数据库，可以确保在主数据库发生故障时，数据依然有备份，并且可以快速切换到从数据库，从而保障了数据的高可用性和系统的容灾能力。",
    "source": "文档中「3. 高可用性」部分的「冗余设计」",
    "hint": "这项技术关注的是“数据”本身的安全，而不是服务的运行状态。"
  },
  {
    "question": "文档中提到的Web应用防火墙（WAF）在网站安全体系中扮演了什么关键角色？",
    "options": [
      "加密客户端与服务器之间的通信数据",
      "防御分布式拒绝服务（DDoS）攻击",
      "防范针对Web应用的恶意流量和攻击（如SQL注入）",
      "对敏感数据进行加密存储"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Web应用防火墙（WAF）专注于保护Web应用程序免受常见的网络攻击，如SQL注入、跨站脚本（XSS）等。它通过分析HTTP/HTTPS流量，过滤和监控恶意请求，从而为应用层提供一道重要的安全防线。这与DDoS防护、数据加密等其他安全措施有所不同。",
    "source": "文档中「4. 安全性」部分的「防御攻击」",
    "hint": "这种安全工具专注于保护“应用层”，而不是网络层或数据存储层。"
  },
  {
    "question": "在处理分布式系统的数据一致性问题时，文档提到了哪两种不同的一致性模型供开发者根据业务场景选择？",
    "options": [
      "水平一致性与垂直一致性",
      "同步一致性与异步一致性",
      "主从一致性与多活一致性",
      "强一致性与最终一致性"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档明确指出，在分布式系统中，可以根据业务需求选择不同的一致性模型。强一致性要求任何数据更新操作完成后，所有后续的读取都能立即看到最新的值，这对数据准确性要求高的场景（如金融交易）至关重要。而最终一致性允许数据在更新后存在一个短暂的不一致窗口，但最终所有副本都会同步到最新状态，这在性能和可用性要求更高的场景中更为常见。",
    "source": "文档中「5. 数据一致性与完整性」部分的「数据一致性」",
    "hint": "一个模型要求“立刻”看到最新数据，另一个模型则允许“稍后”看到。"
  },
  {
    "question": "为了高效地进行故障排查和性能分析，文档推荐采用哪种日志管理策略？",
    "options": [
      "将日志存储在各个服务的本地磁盘上",
      "只记录错误和异常级别的日志",
      "使用集中化日志系统（如ELK Stack）来统一收集和分析日志",
      "为每个微服务创建独立的监控告警"
    ],
    "correctAnswerIndex": 2,
    "explanation": "在分布式或微服务架构中，服务和节点众多，日志分散在各处。集中化日志系统（如ELK Stack、Splunk）可以将所有服务的日志统一收集、存储、索引和分析，这使得跨服务的故障排查和系统行为分析变得极为高效和便捷。",
    "source": "文档中「6. 运维与监控」部分的「日志管理」",
    "hint": "当系统由几十上百个服务组成时，如何才能在一个地方看到所有服务的日志？"
  },
  {
    "question": "根据文档，以下哪项技术组合最能体现“自动化运维”的理念？",
    "options": [
      "Nginx + Redis",
      "TLS/SSL + WAF",
      "Docker + Kubernetes",
      "Prometheus + Grafana"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Docker是一种容器化技术，它将应用及其依赖打包成一个轻量、可移植的容器。Kubernetes则是一个容器编排工具，用于自动化容器的部署、扩展和管理。这两者的结合是现代自动化运维（DevOps）的核心实践，极大地提高了部署效率和系统的可管理性。",
    "source": "文档中「6. 运维与监控」部分的「自动化运维」",
    "hint": "这个组合解决了应用的打包、部署、扩展和自我修复等一系列自动化问题。"
  }
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        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  